There was that line in the SJA episode "Death of the Doctor", where Sarah Jane refers to Ian Chesterton and Barbara Wright, two of the first companions of the First Doctor, as currently teaching at Cambridge, and not having aged since their return to Earth in 1965. Now while I can believe that their retarded ageing process is somehow caused by them travelling in time with the Doctor, I find it hard to accept that their miraculous youthfulness isn't more well known in the world. If people living now were still the same age they were in the sixties, AND were teaching at a public institution and using their real names, it would be a mass media sensation all over the globe. They'd have to hide from government forces who'd want to analyse them in a lab, to get the secret of their eternal youth. I'd like to hear people's opinions on this.